Automated systems for analysis of glass slide specimens using optical or electron microscopes have been available for a number of years. For example, U.S. Pat. No. 5,038,035 to Nishimura is directed to such an automated analyzing/processing apparatus, which includes a computer controlled stage for positioning a single slide in a desired position relative to a microscope optic. Another example of a computer controlled stage can be found in U.S. Pat. No. 4,122,518 to Castleman et al. Such stages to date have been designed to accommodate only one slide at a time, thereby requiring either a human or robotic loading and unloading mechanism for placing each slide in alignment for viewing and analysis. The loading and unloading operation between analysis of each slide is time consuming, and involves an additional risk of breaking slides. For example, an automatic slide loading and unloading mechanism has been marketed by PSI, Inc. as part of its automatic metaphase finder system. This mechanism includes a vacuum system and mechanical arms for lifting a slide from a vertical position in a slide cartridge to a horizontal position on a single slide stage, where a second vacuum system holds the slide to the stage. Another mechanical system then moves the stage to a first locating point and then a second locating point, and then to a position for focusing beneath the viewing lens of the system.
This system is designed to permit sequential analysis of a group of up to sixty slides by the computer controlled system, without attendance by an operator. Although generally acceptable for this purpose, mislocation of a slide during the vacuum pick up and robot arm rotation to horizontal can cause the system to jam if the arm misses the slide during the pick-up operation or misses the slide cartridge slot during the replacement operation. When such misses occur, one or more slides may break and the sequencing and analysis operation is then stalled until an operator attends to the equipment and restarts the operation.
For clinical cytogenetics purposes of identifying and mapping chromosome spreads on a prepared specimen slide, and in particular, for use with a digital karyotype image system such as described in U.S. Pat. No. 4,122,518, it is important to locate the slide accurately relative to the viewing and mapping device. For example, the sixty slide cartridge system described above, for loading and unloading slides in a sequence, requires a first calibration step using a calibration slide for the loaded tray, and then individual slide location calibration between each slide after they are vacuum secured to the single slide tray. Therefore, for single slide stages, each slide position must be calibrated using at least two additional mechanical stops coupled to the computerized system.
It would therefore be desirable to provide a microscope slide stage that can be loaded with multiple slides at once, so that the analysis of all slides can be accomplished in sequence, without interruption of the computer analysis process, or the need to man the machine during the analysis process. It would also be desirable to provide a system for sequencing slides through the analyzer which does not involve the significant risk of breakage inherent in systems which require mechanical movement of the slides once they are loaded for sequenced analysis. Finally, it would be desirable to be able to reference multiple slides to a single fixed location on the slide stage to avoid the need to calibrate the location of each individual slide relative to the slide viewer before analyzing or mapping the slide's image.